For a production process of a beer, there is a well-known step wherein a hop is added to a wort, and then, the mixture is boiled for a preparation procedure before fermentation and lager (see, for example, Patent Literatures 1 and 2 below). Such boiling of wort is carried out for the purpose of giving a bitter taste from the hop to the wort, and removing unnecessary odorant(s) by evaporation, such as dimethylsulfide (DMS), particularly, which is derived from a malt, etc.
Recently, a method for producing a beer in order to emphasize hop-derived odors is also developed (see, for example, Patent Literature 3 below).